EP0540323B1 - Reibwerkstoff und Verfahren zur desen Herstellung - Google Patents

Reibwerkstoff und Verfahren zur desen Herstellung Download PDF

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Publication number
EP0540323B1
EP0540323B1 EP92309899A EP92309899A EP0540323B1 EP 0540323 B1 EP0540323 B1 EP 0540323B1 EP 92309899 A EP92309899 A EP 92309899A EP 92309899 A EP92309899 A EP 92309899A EP 0540323 B1 EP0540323 B1 EP 0540323B1
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EP
European Patent Office
Prior art keywords
friction material
fiber
fibers
friction
mesophase pitch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92309899A
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English (en)
French (fr)
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EP0540323A1 (de
Inventor
Takashi c/o Mitsubishi Gas Chem. Inc. Kojima
Hitoshi c/o Mitsubishi Gas Chem. Inc. Sakamoto
Nobuo Kamioka
Hiroshi Tokumura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Akebono Research and Development Centre Ltd
Mitsubishi Gas Chemical Co Inc
Original Assignee
Akebono Research and Development Centre Ltd
Mitsubishi Gas Chemical Co Inc
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Application filed by Akebono Research and Development Centre Ltd, Mitsubishi Gas Chemical Co Inc filed Critical Akebono Research and Development Centre Ltd
Publication of EP0540323A1 publication Critical patent/EP0540323A1/de
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Publication of EP0540323B1 publication Critical patent/EP0540323B1/de
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
    • F16D69/02—Composition of linings ; Methods of manufacturing
    • F16D69/025—Compositions based on an organic binder
    • F16D69/026—Compositions based on an organic binder containing fibres

Definitions

  • This invention relates to a process for the production of friction materials. More particularly, it relates to a process for producing high-performance friction materials that are markedly improved in friction characteristics, wear resistance, heat resistance and anti-fade quality so that they are particularly suitable for use in brakes and clutches.
  • Friction materials for use in brakes, clutches, etc. are conventionally produced by binding a friction modifier, a filler and a reinforcement with a thermosetting resin such as a phenolic resin, and molding the blend.
  • Friction materials in particular those for use in brakes, are required to exhibit extremely high performance in terms of friction characteristics, wear resistance, heat resistance and anti-fade quality and the greater part of their performance is determined by the performance of the binder resin.
  • Convention friction materials which use phenolic resins and other thermosetting resins as binders, it is impossible to completely eliminate the problems that result from the deterioration of binders with time and their low heat resistance, i.e. the change in friction characteristics, wear, thermal crack and fade.
  • studies have been made of using other thermosetting resins as binders (e.g. furan resins and modified phenolic resins) but, as of today, no friction materials have yet been produced that far excel the prior art versions in performance.
  • a carbon fiber reinforced carbon composite suitable for use as a friction material is described in JP-A-2044019.
  • a pitch containing a specific amount of free carbon is heat treated to generate a specific amount of quinoline-insoluble mesophase which is present in the form of a solid particle in the liquid pitch.
  • the present inventors hence conducted intensive studies in order to develop an industrially advantageous process for the production of high-performance friction materials. As a result, they found that when a pitch that had sulfur and/or an aromatic nitro compound contained in mesophase pitch having low softening point was used as a binder, molding could be achieved under low-temperature conditions to yield a friction material of very good performance.
  • the present invention has been accomplished on the basis of this finding.
  • a friction material comprising one or more fibers selected from metal fibers, organic fibers and inorganic fibers as reinforcement bound with a compounded pitch consisting of 70 to 99% mesophase pitch and 30-1% sulfur, aromatic nitro compound or a combination of sulfur and an aromatic nitro compound, the content of optically anisotropic phase in said mesophase pitch being at least 80% and said mesophase pitch having a softening point of no higher than 270°C.
  • a process for producing the friction material of the above firs aspect comprising binding one or more fibers selected from metal fibers, organic fibers and inorganic fibers with a compounded pitch consisting of 70 to 99% mesophase pitch and 30 to 1% sulfur, aromatic nitro compound or a combination of sulfur and aromatic nitro compound, the content of optically anisotropic phase in said mesophase pitch being at least 80% and said mesophase pitch having a softening point of no higher than 270°C.
  • Fig. 1 is a graph showing the results of the brake dynamo test that was conducted in Examples 1 and 2 and in Comparative Examples 1 and 2.
  • optically anisotropic phase means that part of a sample (a pitch mass that was solidified near ambient temperature and which was polished on a cross-sectional surface) which, when examined with a reflecting optical microscope under crossed Nicols, produces observable brilliance with the sample or the crossed Nicols being rotated (i.e., optically anisotropic).
  • the content of an optically anisotropic phase means the percent area of that optically anisotropic phase as examined with a microscope.
  • mesophase pitch means a pitch that contains this optically anisotropic phase.
  • softening point means the solid-liquid transition temperature as measured on the pitch with a Kohka type flow tester.
  • aromatic nitro compounds may be used either independently or as admixtures; if desired, they may contain isomers. For reasons of commercial availability and easy handling, dinitronaphthalene can be used with advantage.
  • a pitch that consists of 70 - 99% of mesophase pitch and 30 - 1% of sulfur and/or an aromatic nitro compound is used as a binder for friction materials, the content of an anisotropic phase, as defined above, in said mesophase pitch being at least 80% and said mesophase pitch having a softening point of no higher than 270°C.
  • the content of sulfur and/or an aromatic nitro compound in the pitch to be used in the present invention is less than 1%, satisfactory impregnation cannot be achieved at low temperature; if their content is more than 30%, they will remain unreacted in the molding. In either case, the resulting friction material has lower strength. This is also true with the case of using mesophase pitch that softens at higher than 270°C; satisfactory impregnation is not achieved at low temperature and only poor molding will result.
  • the compounded pitch described above is used as a binder to produce a friction material.
  • the friction material produced contains a reinforcement such as a metal fiber, an organic fiber or an inorganic fiber.
  • a reinforcement such as a metal fiber, an organic fiber or an inorganic fiber.
  • Exemplary metal fibers include steel fibers and copper fibers;
  • exemplary organic fibers include aramid fibers and aramid pulp fibers;
  • exemplary inorganic fibers include glass fibers, Al 2 O 3 -SiO 2 fibers, potassium titanate fibers and rock wool.
  • the reinforcement is preferably used in combination with other additives such as a friction modifier and a filler.
  • a friction modifier and a filler designate metallic, inorganic or organic powders and short fibers, as specifically exemplified by a copper powder, an iron powder, a zinc powder, BaSO 4 , Sb 2 O 3 , Fe 3 O 4 , ZrSiO 4 etc.
  • Other powders and short fibers may be used in accordance with a specific object but without any other limitations.
  • the amount in which the binder is to be used in the present invention is not limited to any particular value but in the case of extreme overdose or underdose, the strength of the friction material produced will decrease.
  • the binder is preferably used in an amount ranging from 3 to 40%.
  • the ingredients can be mixed by any method, whether wet or dry, that is employed in the production of common friction materials.
  • hot compression molding and any other hot molding methods can be employed that are applied to the molding of common friction materials.
  • the compounded pitch to be used as a binder in the present invention softens at a temperature 5 - 80°C lower than the softening point of the mesophase pitch which is one ingredient of the pitch.
  • the compounded pitch exhibits satisfactory fluidity and impregnation even at low temperatures of 200°C and below.
  • sulfur or aromatic nitro compound which is the ingredient to be compounded undergoes vigorous reaction at temperatures exceeding about 180°C and, after a heat treatment conducted at 240°C and above, there occurs conversion to a substantially dense carbonaceous material having high heat stability.
  • the carbonaceous material resulting from the compounded pitch will experience only limited weight loss while working as a very stable binder in a temperature range from ambient up to about 1000°C; hence, a friction material can be molded from this carbonaceous material even at low temperatures of about 180 - 400°C.
  • the friction material produced by the process of the present invention is molded at comparatively low temperatures and yet it experiences only limited weight loss while exhibiting high strength in a temperature range of from ambient up to about 1000°C, with the attendant advantage of exhibiting extremely high performance in terms of friction characteristics, wear resistance, heat resistance and anti-fade quality.
  • the friction material thus molded may optionally be put to use after it is subjected to a heat treatment at 1000°C and below in an inert gas atmosphere such as a nitrogen gas.
  • Steel fibers (45 parts), BaSO 4 (10 parts), Sb 2 O 3 (3 parts), ZrSiO 4 (10 parts), a graphite powder (30 parts), a Zn powder (2 parts) and a mesophase pitch (9 parts) that had a softening point of 245°C and whose content of optically anisotropic phase was 100% were dry mixed with a mixer for 5 min.
  • the blend was subjected to preliminary molding, placed in a mold and hot molded at 600°C to prepare a braking pad.
  • the pad was subjected to a dynamo test as in Comparative Example 1 and the result is shown by curve a in Fig. 1. Upon completion of the test, the pad was found to have undergone a total wear of 0.46 mm. The test result shows that the pad of Example 1 was molded at low temperature but that it exhibited as high performance as the pad of Comparative Example 1 in terms of friction characteristics, wear resistance, heat resistance and anti-fade quality.
  • the pad was subjected to a dynamo test as in Comparative Example 1 and the result is shown by curve b in Fig. 1. Upon completion of the test, the pad was found to have undergone a total wear of 0.44 mm. The test result shows that despite molding at low temperature, the pad of Example 2 exhibited as high performance as the pad of Comparative Example 1 in terms of friction characteristics, wear resistance, heat resistance and anti-fade quality.
  • friction materials that exhibit consistent friction characteristics over a broad temperature range can be produced in an economically advantageous way under low-temperature molding conditions.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Braking Arrangements (AREA)

Claims (15)

  1. Reibungswerkstoff, umfassend eine oder mehrere Faserart(en), ausgewählt aus Metallfasern, organischen Fasern und anorganischen Fasern, als Verstärkung, die mit einer Pechmischung aus 70 - 99% Mesophasepech und 30 - 1% Schwefel, einer aromatischen Nitroverbindung oder einer Kombination aus Schwefel und einer aromatischen Nitroverbindung gebunden ist (sind), wobei der Gehalt an optisch anisotroper Phase in dem Mesophasepech mindestens 80% beträgt und das Mesophasepech einen Erweichungspunkt von nicht mehr als 270°C aufweist.
  2. Reibungswerkstoff nach Anspruch 1, wobei die aromatische Nitroverbindung aus Nitrobenzol, Dienitrobenzol, Dinitrotoluol, Dinitrocresol, Nitronaphthalin, Dinitronaphthalin, Nitroanthracen, Dinitroanthracen und Mischungen derselben ausgewählt ist.
  3. Reibungswerkstoff nach Anspruch 1 oder 2, wobei die Metallfaser aus einer Stahlfaser oder Kupferfaser besteht.
  4. Reibungswerkstoff nach Anspruch 1 oder 2, wobei die organische Faser aus einer Aramidfaser oder Aramidpulpefaser besteht.
  5. Reibungswerkstoff nach Anspruch 1 oder 2, wobei die anorganische Faser aus einer Glasfaser, Al2O3-SiO2-Faser, Kaliumtitanatfaser oder Steinwolle besteht.
  6. Reibungswerkstoff nach einem der Ansprüche 1 bis 5, der zusätzlich ein Reibungsmodifizierungsmittel und einen Füllstoff enthält.
  7. Reibungswerkstoff nach Anspruch 6, wobei das Reibungsmodifizierungsmittel und der Füllstoff jeweils aus einem (einer) metallischen, anorganischen oder organischen Pulver oder kurzen Faser bestehen.
  8. Reibungswerkstoff nach Anspruch 6, wobei das Reibungsmodifizierungsmittel und der Füllstoff jeweils aus Kupferpulver, Eisenpulver, Zinkpulver, BaSO4, Sb2O3, Fe3O4 und ZrSiO4 ausgewählt sind.
  9. Reibungswerkstoff nach einem der Ansprüche 1 bis 8, wobei das Bindemittel in einer Menge von 3 - 40% auf der Basis des Gewichts des Reibungswerkstoffs verwendet wird.
  10. Verfahren zur Herstellung des Reibungswerkstoffs nach einem der Ansprüche 1 bis 9 durch Binden einer oder mehrerer Faserart(en), ausgewählt aus Metallfasern, organischen Fasern und anorganischen Fasern, mit einer Pechmischung aus 70 - 99% Mesophasepech und 30 - 1% Schwefel, einer aromatischen Nitroverbindung oder einer Kombination aus Schwefel und einer aromatischen Nitroverbindung, wobei der Gehalt an optisch anisotroper Phase in dem Mesophasepech mindestens 80% beträgt und das Mesophasepech einen Erweichungspunkt von nicht höher als 270°C aufweist.
  11. Verfahren nach Anspruch 10, wobei der Reibungswerkstoff durch Heißformen hergestellt wird.
  12. Verfahren nach Anspruch 11, wobei das Heißformen aus einem Heißpressen besteht.
  13. Verfahren nach Anspruch 11 oder 12, wobei die Formgebungstemperatur 180 - 400°C beträgt.
  14. Verfahren nach Anspruch 11 oder 12, wobei der Reibungswerkstoff nach dem Ausformen in einer inerten Atmosphäre bei einer Temperatur von 1000°C und darunter wärmebehandelt wird.
  15. Verfahren nach Anspruch 14, wobei die inerte Atmosphäre aus einer Stickstoffatmosphäre besteht.
EP92309899A 1991-10-29 1992-10-29 Reibwerkstoff und Verfahren zur desen Herstellung Expired - Lifetime EP0540323B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP31000991A JP3154008B2 (ja) 1991-10-29 1991-10-29 摩擦材料の製造方法
JP310009/91 1991-10-29

Publications (2)

Publication Number Publication Date
EP0540323A1 EP0540323A1 (de) 1993-05-05
EP0540323B1 true EP0540323B1 (de) 1996-06-05

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EP92309899A Expired - Lifetime EP0540323B1 (de) 1991-10-29 1992-10-29 Reibwerkstoff und Verfahren zur desen Herstellung

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US (1) US5279777A (de)
EP (1) EP0540323B1 (de)
JP (1) JP3154008B2 (de)
DE (1) DE69211293T2 (de)

Families Citing this family (10)

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Publication number Priority date Publication date Assignee Title
US5753018A (en) * 1997-04-14 1998-05-19 General Motors Corporation Resin mixture for friction materials
JP4540890B2 (ja) * 2001-07-12 2010-09-08 日本碍子株式会社 ブレーキ材
US8689671B2 (en) 2006-09-29 2014-04-08 Federal-Mogul World Wide, Inc. Lightweight armor and methods of making
JP5331428B2 (ja) * 2008-09-29 2013-10-30 日立オートモティブシステムズ株式会社 ブレーキ摩擦材
JP5702090B2 (ja) * 2010-09-03 2015-04-15 日産自動車株式会社 摩擦材
TW201237235A (en) * 2011-03-11 2012-09-16 ying-hong Ji Ditch cover the structure of mosquito odor
WO2014009341A1 (de) 2012-07-11 2014-01-16 Basf Se Chemisches umsetzungsverfahren in einer dispersion
JP7078359B2 (ja) * 2017-06-27 2022-05-31 曙ブレーキ工業株式会社 焼結摩擦材及び焼結摩擦材の製造方法
DE102017130491A1 (de) * 2017-12-19 2019-06-19 Federal-Mogul Friction Products Gmbh Hybrid-Reibbelagmaterial sowie daraus hergestellte Bremsbeläge und Verfahren zu deren Herstellung
CN112968625B (zh) * 2021-03-09 2022-06-24 上海交通大学 一种具有摩擦正极性的玻璃纤维布材料及其制备方法和应用

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Also Published As

Publication number Publication date
JP3154008B2 (ja) 2001-04-09
DE69211293T2 (de) 1996-10-31
US5279777A (en) 1994-01-18
DE69211293D1 (de) 1996-07-11
EP0540323A1 (de) 1993-05-05
JPH05117634A (ja) 1993-05-14

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